Abstract

This thesis developed a new CO vertical column density product from near IR observations of the SCIAMACHY instrument aboard ENVISAT. To correct the effects of the ice layer on the SCIAMACHY near-IR detectors a normalization procedure based on collocated MOPITT observations over the oceans was developed. Although in this thesis only SCIAMACHY observations for effective cloud fractions below 20% are used, the remaining effects of clouds can still be large due to the higher cloud top albedo. Thus, a newly developed correction scheme is applied, which explicitly considers the cloud fraction, cloud top height and surface albedo of individual observations. The resulting SCIAMACHY CO data is well suited for the investigation of the CO distribution over the continents, where important emission sources are located. This thesis compared the new SCIAMACHY CO data set, and also observations from the MOPITT instrument, to the results from three chemistry climate models (MATCH, EMAC, and GEOS); the focus of this comparison is on regions with strong CO emissions (from biomass burning or anthropogenic sources). The comparison indicates that over most of these regions the simulated CO vertical column densities are systematically smaller than the satellite observations with the largest differences compared to the SCIAMACHY observations. Because of the high sensitivity of the SCIAMACHY observations for the lowest part of the atmosphere, this indicates that especially close to the surface the model simulations systematically underestimate the true atmospheric CO concentrations, probably caused by an underestimation of the true CO emissions by current emission inventories.